Organic silicon compound, method of its production, and photoreceptor for electrophotography incorporating it

ABSTRACT

The present invention is directed to a silicon-containing triarylamine compound represented by the formula (1): ##STR1## wherein Q 2  and Q 3  independently represent a hydrogen atom or --CH 2  SiR 1  R 2  R 3  group (R 1 , R 2  and R 3 , which may be identical or not, independently represent an alkyl group, cycloalkyl group, aralkyl group or aryl group which may be substituted); Ar 1 , Ar 2  and Ar 3  independently represent an arylene group which may be substituted; Q 1  represents a --CH 2  SiR 1  R 2  R 3  group, --CH 2  SiR 1  R 2  R 4  group (R 4  represents the following: ##STR2## wherein Q 2  and Q 3  independently represent a hydrogen atom) or --CH 2  SiR 1  R 4  R 4  group, a method of its production and a photoreceptor for electrophotography incorporating it as a charge transport material. The photoreceptor is very excellent in sensitivity and durability.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a silicon-containing triarylaminecompound, a method of its production and a high-sensitivityhigh-durability photoreceptor for electrophotography incorporating saidsilicon-containing triarylamine compound as the charge transportmaterial.

2. Description of the Prior Art

In recent years, there have been noticeable improvements in copyingmachines and printers based on electrophotography. A wide variety of newmodels of different shapes, types and functions have been developedaccording to uses, and various photoreceptors for such new models havebeen developed accordingly.

Traditionally, photoreceptors for electrophotography have been basedmainly on an inorganic compound from the viewpoint of its sensitivityand durability. Examples of such inorganic compounds include zinc oxide,cadmium sulfide and selenium. However, these substances are often toxic,thus posing problems of disposal and environmental pollution. Inaddition, when using selenium, which offers good sensitivity, it isnecessary to form a thin film on a conductive substrate by vacuumdeposition, etc., which results in poor productivity and increasedproduction cost.

Amorphous silicon has recently drawn much attention as an inorganicphotoreceptor free of environmental pollution, and research anddevelopment activities are in progress. However, the use of the plasmaCVD method for film formation results in extremely poor productivity andincreased photoreceptor production cost and running cost, thoughexcellent sensitivity is obtained.

On the other hand, organic photoreceptors have the advantage of beingfree of environmental pollution since they are burnable, which permitseasy mass production since they are also coatable for thin films. Theseaspects are advantageous in that significant cost reduction is possibleand a wide range of shapes can be obtained according to uses. It shouldbe noted, however, that organic photoreceptors involve some problems tobe solved as to sensitivity and durability; there are strong demands forthe development of an organic photoreceptor with high sensitivity andhigh durability.

Various methods have been proposed to improve the sensitivity of organicphotoreceptor, but current efforts are drawn to photoreceptors ofdouble-layered photoconductive structure in which functions are allottedto a charge generation layer and a charge transport layer. For example,the charge generated in the charge generation layer in response toexposure is injected to the charge transport layer, through which it istransported to the surface of the photoreceptor, where the surfacecharge is neutralized and an electrostatic latent image is formedthereon. Thus, in the double-layered photoconductive structure type ascompared with the single-layered structure type, the generated charge isless likely to be trapped, and the charge can be more efficientlytransported to the surface of the photoreceptor (U.S. Pat. No.2,803,541).

As the organic charge generation material for the charge generationlayer, a compound which absorbs the energy of the irradiated light andefficiently generates a charge is selected and used. Examples of suchcompounds include an azo pigment (Japanese Patent Publication Open toPublic Inspection No. 14967/1979), a metal-free phthalocyanine pigment(Japanese Patent Publication Open to Public Inspection No. 143346/1985),a metallophthalocyanine pigment (Japanese Patent Publication Open toPublic Inspection No. 16538/1975) and a squarylium salt (Japanese PatentPublication Open to Public Inspection No. 27033/1978).

As the charge transport material for the charge transport layer, it isnecessary to select a compound which offers a high efficiency of chargeinjection from the charge generation layer and a high charge mobility inthe charge transport layer. To meet these requirements, a compoundhaving a low ionization potential or a compound which easily releases acationic radical is selected. Examples of such compounds proposedinclude a triarylamine derivative (Japanese Patent Publication Open toPublic Inspection No. 47260/1978), a hydrazone derivative (JapanesePatent Publication Open to Public Inspection No. 101844/1982), anoxadiazole derivative (Japanese Patent Examined Publication No.5466/1959), a pyrazoline derivative (Japanese Patent ExaminedPublication No. 4188/1977), a stilbene derivative (Japanese PatentPublication Open to Public Inspection No. 198043/1983), atriphenylmethane derivative (Japanese Patent Examined Publication No.555/1970), and a 1,3-butadiene derivative (Japanese Patent PublicationOpen to Public Inspection No. 287257/1987).

As stated above, however, these organic photoreceptors are lower thaninorganic photoreceptors in charge mobility, and their sensitivityremains unsatisfactory.

Also, in a series of electrophotographic processes of charging,exposure, development, toner transfer and discharging, the photoreceptoris subject to extremely severe conditions and its ozone resistance andabrasion resistance are of great concern; improvements in thesedurability properties are demanded, but no satisfactory photoreceptorshave been developed.

Above all, triarylamine has been investigated for a large number ofderivatives, including monotriarylamine (Japanese Patent PublicationOpen to Public Inspection Nos. 195254/1982, 118147/1989 and118142/1989), bis(diarylamino)benzene (Japanese Patent Publication Opento Public Inspection Nos. 144250/1980, 118144/1989 and 118146/1989) andbistriarylamine (Japanese Patent Publication Open to Public InspectionNos. 27033/1978, 35140/1981, 52756/1981 and 142647/1989).

However, monotriarylamine has drawbacks of insufficient charge mobilityand a lack of stability, through it is generally easy to synthesize. Asfor bis(diarylamino)benzene and bistriarylamine, they have drawbacks ofa lack of stability and difficult synthesis, though they offer a fairlevel of charge mobility. Also, these triarylamine derivatives all havebeen suggested to pose a problem of a lack of compatibility with binderresins.

As stated above, conventional organic photoreceptors such astriarylamine derivatives have many drawbacks, and there are strongdemands for improvements to overcome these drawbacks in the relevanttechnical field.

It should be noted that a silicon-containing triarylamine compound whichis similar to the present invention is disclosed in U.S. Pat. No.2,960,517, but it is a monosilyltriphenylamine compound and isunsuitable for use as a charge transport material for photoreceptor forelectrophotography because it is liquid at normal temperature. Inaddition, it is produced by reaction of a bromophenylalkylsilanecompound and an alkali metal salt of amine, and these starting materialsare not easily available and this reaction requires severe conditionsboth for reaction temperature and for reaction time.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel compoundwhich has excellent charge mobility and excellent stability, which iscompatible with binder resin and which serves well as a charge transportmaterial, whereby the problems described above are solved.

It is another object of the present invention to provide a method ofproducing said novel compound.

It is still another object of the present invention to provide ahigh-sensitivity high-durability photoreceptor for electrophotographywhich incorporates said novel compound as the charge transport material.

With the aim of solving the problems described above, the presentinventors developed the present invention.

Accordingly, a mode of the present invention relates to asilicon-containing triarylamine compound represented by the formula (1):##STR3## wherein Q₂ and Q₃ independently represent a hydrogen atom or--CH₂ SiR₁ R₂ R₃ group (R₁, R₂ and R₃, which may be identical or not,independently represent an alkyl group, cycloalkyl group, aralkyl groupor aryl group which may be substituted); Ar₁, Ar₂ and Ar₃ independentlyrepresent an arylene group which may be substituted; Q₁ represents a--CH₂ SiR₁ R₂ R₃ group, --CH₂ SiR₁ R₂ R₄ group (R₄ represents thefollowing: ##STR4## wherein Q₂ and Q₃ independently represent a hydrogenatom) or --CH₂ SiR₁ R₄ R₄ group.

Another mode of the present invention relates to a method of producing asilicon-containing triarylamine compound characterized by reaction of aGrignard reagent represented by the formula (1)': ##STR5## wherein Q₂ 'and Q₃ ' independently represent a hydrogen atom or --CH₂ MgX (Xrepresents a halogen atom); Q₁ ' represents --CH₂ MgX; Ar₁, Ar₂ and Ar₃have the same definitions as above, with a silane compound representedby the formula (6):

    X.sub.1 SiR.sub.1 'R.sub.2 'R.sub.3 '                      (6)

wherein X₁ represents a halogen atom or alkoxy group; none, one or twoof R₁ ', R₂ ' and R₃ ' independently represent a halogen atom or alkoxygroup while the remaining one, two or three independently represent analkyl group, cycloalkyl group, aralkyl group or aryl group which may besubstituted.

Still another mode of the present invention relates to a method ofproducing a silicon-containing triarylamine compound characterized byGrignard coupling reaction between a compound represented by the formula(7):

    R.sub.1 R.sub.2 R.sub.3 "SiCH.sub.2 MgX                    (7)

wherein R₃ " is identical with R₃ (R₃ has the same definition as above)or represents --CH₂ MgX; R₁, R₂ and X have the same definitions asabove, and a halogenated triarylamine compound in the presence of acoupling catalyst.

Still yet another mode of the present invention relates to aphotoreceptor for electrophotography essentially comprising a conductivesubstrate and a light-sensitive layer formed thereon characterized bythe containment of a silicon-containing triarylamine compound of thepresent invention in said light-sensitive layer.

The silicon-containing triarylamine compound represented by the formula(1) of the present invention can be specifically represented by theformulas (2) through (5).

A compound represented by the formula (2): ##STR6## wherein R₁, R₂, R₃,Ar₁, Ar₂ and Ar₃ have the same definitions as above.

A compound represented by the formula (3): ##STR7## wherein R₁, R₂, Ar₁,Ar₂ and Ar₃ have the same definitions as above, and Q₂ and Q₃ representa hydrogen atom.

A compound represented by the formula (4): ##STR8## wherein R₁, Ar₁, Ar₂and Ar₃ have the same definitions as above, and Q₂ and Q₃ represent ahydrogen atom.

A compound represented by the formula (5): ##STR9## wherein R₁, R₂, R₃,Ar₁, Ar₂ and Ar₃ have the same definitions as above, and Q₂ and Q₃represent a hydrogen atom.

DETAILED DESCRIPTION OF THE INVENTION

With respect to the formulas (1) through (5), Ar₁, Ar₂ and Ar₃independently represent an arylene group which may be substituted.Examples of the arylene group include phenylene, naphthylene andanthranylene. The substituent is normally an alkyl group having a carbonnumber of 4 or less, exemplified by methyl and ethyl.

Q₂ and Q₃ independently represent a hydrogen atom or --CH₂ SiR₁ R₂ R₃group wherein R₁, R₂ and R₃, which may be identical or not,independently represent an alkyl group, cycloalkyl group, aralkyl groupor aryl group which may be substituted.

When R₁, R₂ and R₃ are alkyl groups, the alkyl group is a linear orbranched C₁₋₆ alkyl group for the compound represented by the formula(2) or (3); for the compound represented by the formula (4), the alkylgroup is a linear or branched C₁₋₁₀ alkyl group; for the compoundrepresented by the formula (5), the alkyl group is a linear or branchedC₁₋₈ alkyl group. Examples of such alkyl groups include methyl, ethyl,isopropyl, n-propyl, n-butyl, isobutyl, s-butyl and t-butyl. This alkylgroup may be substituted, and the substituent is normally an alkoxygroup, with preference given to methoxy and ethoxy.

When R₁, R₂ and R₃ are cycloalkyl groups, they are exemplified bycycloalkyl groups having a carbon number of 8 or less which may besubstituted with an alkyl group or another substituent. Examples of suchcycloalkyl groups include cyclopropyl, cyclopentyl, cyclohexyl,cycloheptyl and cyclooctyl.

When R₁, R₂ and R₃ are aralkyl groups, examples of their aryl groupmoiety include phenyl, naphthyl and anthranyl which may be substitutedwith an alkyl group, alkoxy group or another substituent; examples ofthe alkylene group moiety include those having a carbon number of 1 to4, with preference given to methylene. Examples of the aralkyl groupinclude benzyl, p-methylbenzyl and m-methylbenzyl groups.

When R₁, R₂ and R₃ are aryl groups, examples of the aryl group includephenyl, naphthyl and anthranyl which may be substituted with an alkylgroup, alkoxy group or another substituent, with preference given tophenyl.

R₁, R₂ and R₃ are groups which may be identical or not. When one or moreof R₁, R₂ and R₃ are not identical with the other member(s), or whenthey are alkyl groups having a carbon number of 5 or more for thecompound represented by the formula (2), 7 or more for the compoundrepresented by the formula (3), 11 or more for the compound representedby the formula (4), or 8 or more for the compound represented by theformula (5), the compound occurs as a liquid or grease at normaltemperature and is thus undesirable for use as a charge transportmaterial.

Q₁ represents a --CH₂ SiR₁ R₂ R₃ group, --CH₂ SiR₁ R₂ R₄ group or --CH₂SiR₁ R₄ R₄ group wherein R₄ represents the following: ##STR10## whereinQ₂ and Q₃ represent a hydrogen atom; Ar₂ and Ar₃ represent an aryl groupwhich may be substituted.

The silicon-containing triarylamine compounds represented by theformulas (1) through (5) can be produced by one of the methods (A) and(B) described below. Method (A):

The method in which reaction is carried out between a Grignard reagentrepresented by the formula (1)': ##STR11## wherein Q₂ ' and Q₃ 'independently represent a hydrogen atom or --CH₂ MgX (X represents ahalogen atom); Q₁ ' represents --CH₂ MgX; Ar₁, Ar₂ and Ar₃ have the samedefinitions as above, and a silane compound represented by the formula(6):

    X.sub.1 SiR.sub.1 'R.sub.2 'R.sub.3 '                      (6)

wherein X₁ represents a halogen atom or alkoxy group; none, one or twoof R₁ ', R₂ ' and R₃ ' independently represent a halogen atom or alkoxygroup while the remaining one, two or three independently represent analkyl group, cycloalkyl group, aralkyl group or aryl group which may besubstituted.

With respect to the formula (1)', the halogen atom represented by X maybe any one of chlorine, bromine and iodine.

The Grignard reagent represented by the formula (1)' for the presentinvention can be prepared by a known method using a halogenomethylatedtriarylamine compound and metallic magnesium as starting materials.Specifically, the Grignard reagent represented by the formula (1)' isprepared using the halogenomethylated triarylamine compound and metallicmagnesium in an ether solvent. The halogenomethylated triarylaminecompound can easily be obtained by halogenomethylating a triarylaminecompound by a known method. Examples of ether solvents include diethylether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether,diethylene glycol dimethyl ether, diethylene glycol diethyl ether,tetrahydrofuran, dioxane, diisopropyl ether and di-n-butyl ether, withpreference given to diethyl ether and tetrahydrofuran.

To the ether solution of the Grignard reagent thus obtained, the silanecompound represented by the formula (6), after being diluted in theabove-mentioned ether solvent if necessary, is added dropwise.

Here, when X₁ in the formula (6) represents a halogen atom, it may beany one of chlorine, bromine and iodine. When it represents an alkoxygroup, it may be linear or branched, and its carbon number is preferably1 to 4. Examples of such alkoxy groups include methoxy, ethoxy, propoxy,isopropoxy and n-butoxy. As stated above, X₁ represents a halogen atomor alkoxy group, but a halogen atom is preferred from the viewpoint ofreactivity.

The amount of the silane compound, relative to the amount of theGrignard reagent, is normally 2.5 to 4.0 equivalents, preferably 3equivalents for the compound represented by the formula (2), 0.3 to 1.0equivalent, preferably 0.5 equivalent for the compound represented bythe formula (3), 0.3 to 0.5 equivalent, preferably 0.33 equivalent forthe compound represented by the formula (4), and 0.7 to 1.5 equivalents,preferably 1 equivalent for the compound represented by the formula (5).Dropwise addition time is normally 30 minutes to 5 hours, preferably 30minutes to 2 hours. Dropwise addition temperature is normally -50° C. to100° C., preferably -10° C. to 50° C. Cooling or heating is added asneeded. After completion of the addition, the mixture is stirred underreflux to the reaction end point. After completion of the reaction,hydrolysis is carried out, followed by treatment with a common manner toyield the silymethylated triarylamine compound represented by theformula (1) at high yield.

The methods for production of the compounds represented by the formulas(2) through (5) using the method (A) are described in more detail.First, to prepare the compound represented by the formula (2), theGrignard reagent of the formula (1)' wherein Q₂ ' and Q₃ ' are --CH₂ MgXis reacted with the silane compound of the formula (6) wherein all of R₁', R₂ ' and R₃ ' are independently an alkyl group, cycloalkyl group,aralkyl group or aryl group which may be substituted.

To prepare the compound represented by the formula (3), the Grignardreagent of the formula (1)' wherein Q₂ ' and Q₃ ' are hydrogen atoms isreacted with the silane compound of the formula (6) wherein one of R₁ ',R₂ ' and R₃ ' independently represents a halogen atom or alkoxy groupwhile the remaining two independently represent an alkyl group,cycloalkyl group, aralkyl group or aryl group which may be substituted.

To prepare the compound represented by the formula (4), the Grignardreagent of the formula (1)' wherein Q₂ ' and Q₃ ' are hydrogen atoms isreacted with the silane compound of the formula (6) wherein two of R₁ ',R₂ ' and R₃ ' independently represent a halogen atom or alkoxy groupwhile the remaining one is an alkyl group, cycloalkyl group, aralkylgroup or aryl group which may be substituted.

To prepare the compound represented by the formula (5), the Grignardreagent of the formula (1)' wherein Q₂ ' and Q₃ ' are hydrogen atoms isreacted with the silane compound of the formula (6) wherein all of R₁ ',R₂ ' and R₃ ' are independently an alkyl group, cycloalkyl group,aralkyl group or aryl group which may be substituted. Method (B):

The method in which Grignard coupling reaction is carried out betweenthe compound represented by the formula (7):

    R.sub.1 R.sub.2 R.sub.3 "SiCH.sub.2 MgX                    (7)

wherein R₃ " is identical with R₃ (R₃ has the same definition as above)or represents --CH₂ MgX; R₁, R₂ and X have the same definitions asabove, and a halogenated triarylamine compound in the presence of acoupling catalyst.

With respect to the formula (7), X represents a halogen atom as above,and it may be any one of chlorine, bromine and iodine.

The compound represented by the formula (7) can be obtained by Grignardreaction between R₁ R₂ R₃ "SiCH₂ X and metallic magnesium in thepresence of the above-mentioned ether solvent by a known method.

To the ether solution of the compound represented by the formula (7)thus obtained, a Grignard coupling catalyst is added, and an ethersolution of the halogenated triarylamine compound is added dropwise andreaction is carried out.

The halogenated triarylamine compound can be synthesized by any knownmethod. For example, it can be obtained by Ullmann reaction between adiarylamine compound and a dihalogenated aryl compound [Berichte, vol.36, p. 2382 (1903)].

It can also be obtained by directly halogenating a triarylamine compoundwith a known halogenating agent. There is no limitation on the choice ofthe halogen atom; any of chlorine atom, bromine atom and iodine atom canbe used.

The amount of the halogenated triarylamine compound, relative to theamount of the Grignard reagent, is normally 0.5 to 1.0 equivalent,preferably 0.8 to 1.0 equivalent for the compound represented by theformula (2), 1.5 to 3.0 equivalents, preferably 2.0 equivalents for thecompound represented by the formula (3), and 0.7 to 1.5 equivalents,preferably 1 equivalent for the compound represented by the formula (5).Dropwise addition time is normally 15 minutes to 3 hours, preferably 15minutes to 1 hour. Dropwise addition temperature is normally -50° C. to100° C., preferably 0° C. to 50° C. Cooling or heating is added asneeded. A known transition metal catalyst is used as the Grignardcoupling catalyst (Kagaku no Ryoiki, extra No. 117, p. 45). Examples ofthe Grignard coupling catalyst include Li₂ CuCl₄, CuBr, CuCl, NiCl₂(dppe)₂ (dppe=bis(diphenylphosphino)ethane), NiCl₂ (dppp).sub. 2(dppp=bis(diphenylphosphino)propane), NiCl₂ (dmpe)₂(dmpe=bis(dimethylphosphino)ethane), NiCl₂ (PPh₃) (Ph=phenyl group),NiCl₂, Pd(PPh₃)₄, AgBr and AgNO₃, with preference given to an Ni complexor Pd complex.

The addition amount of these Grignard coupling catalysts is normally 10ppm to 5% by weight to the amount of the monohalogenated triarylaminecompound.

After completion of the addition, the mixture is stirred under refluxand heating to the reaction end point. After completion of the reaction,treatment is carried out with a common manner to yield thesilylmethylated triarylamine compound represented by the formula (1) athigh yield.

The methods for production of the compounds represented by the formulas(2), (3) and (5) using the method (B) are described in more detail.First, to prepare the compound represented by the formula (2), Grignardcoupling reaction is carried out between the compound of the formula (7)wherein R₃ " is R₃ and a tris(halogenoaryl)amine compound in thepresence of a coupling catalyst.

To prepare the compound represented by the formula (3), Grignardcoupling reaction is carried out between the compound of the formula (7)wherein R₃ " represents CH₂ MgX and a monohalogenated triarylaminecompound in the presence of a coupling catalyst.

To prepare the compound represented by the formula (5), Grignardcoupling reaction is carried out between the compound of the formula (7)wherein R₃ " is R₃ and a monohalogenated triarylamine compound in thepresence of a coupling catalyst.

The silicon-containing triarylamine compound thus obtained is suitablefor use as a charge transport material for a photoreceptor forelectrophotography since the silymethyl group inductive effect resultsin cation radical stabilization and increased positive charge mobility.As stated above, a silicon-containing triarylamine compound is disclosedin U.S. Pat. No. 2,960,517, but it is a monosilyltriphenylaminecompound, essentially different from the silicon-containing triarylaminecompound of the present invention, and is unsuitable for use as amaterial for a photoreceptor for electrophotography because it is liquidat normal temperature. In addition, its production is based on reactionof a bromophenylalkylsilane compound and an alkali metal salt of amine,and these starting materials are not easily available. Furthermore, thisreaction requires severe conditions both for reaction temperature andfor reaction time. Conversely, the production method of the presentinvention uses less expensive materials and produces the desiredcompound at room temperature at high yield in short time.

In addition, a large number of silylmethylated aryl compounds havetraditionally been known as cation radical stabilizing compounds,including those described in the Journal of Organometallic Chemistry,vol. 29, p. 33 (1971), but all of them are benzene derivatives such astrimethylsilylmethylbenzene and trimethylsilymethylaniline. In contrast,in the present invention, conversion to a triarylamine derivativepermits further cation radical stabilization and makes it possible tofurther increase the charge mobility.

Also, these compounds are stable against oxidation by ozone generated inthe electrophotographic process, thus yielding a photoreceptor forelectrophotography with high sensitivity and high durability.

The silicon-containing triarylamine compound of the present invention ishereinafter described in more detail by means of Example Compounds (8)through (77), but the invention is not limited to them. ##STR12##

These compounds are soluble in a large number of solvents, includingaromatic solvents such as benzene, toluene, xylene, tetralin andchlorobenzene; halogen solvents such as dichloromethane, chloroform,trichloroethylene and tetrachloroethylene and carbon tetrachloride;ester solvents such as methyl acetate, ethyl acetate, propyl acetate,methyl formate and ethyl formate; ketone solvents such as acetone andmethyl ethyl ketone; ether solvents such as diethyl ether, dipropylether, dioxane and tetrahydrofuran; alcohol solvents such as methanol,ethanol and isopropyl alcohol; and other solvents such as dimethylformamide, dimethylacetamide and dimethylsulfoxide.

In the production of a photoreceptor for electrophotography, forexample, a charge generation layer and a charge transport layer areformed as thin films on a conductive substrate. Examples of substanceswhich can be used as the conductive substrate include metals such asaluminum and nickel, metal-deposited polymer films and metal-laminatedpolymer films, which form the conductive substrate in the form of adrum, sheet or belt.

The charge generation layer comprises a charge generation material, andin addition a binder and other additives added as needed, and can beprepared by vacuum deposition, plasma CVD, coating and other methods.

Any organic or inorganic material can be used as the charge generationmaterial with no limitation, as long as it is capable of absorbing thelight of a specific wavelength irradiated and of efficiently generatinga charge; however, it is preferable to use an organic material sinceinorganic materials pose problems of environmental pollution and economyas stated above.

Examples of the organic charge generation material include perylenepigment, condensed ring quinone pigment, metal-free phthalocyaninepigment, metallophthalocyanine pigment, bisazo pigment, trisazo pigment,thiapyririum salt, squarylium salt and azulenium pigment, which can bedispersed in binder and used to form a charge generation layer bycoating. Examples of the inorganic charge generation material includeselenium, selenium alloy, cadmium sulfide, zinc oxide, amorphous siliconand amorphous silicon carbide. Particularly, X-form metal-freephthalocyanine pigment ranks highest in sensitivity in the semiconductorlaser wavelength region and dibromoanthanthrone pigment ranks highest insensitivity in the visible light region.

The thickness of the charge generation layer thus formed is preferably0.1 to 2.0 μm, more preferably 0.1 to 1.0 μm.

Next, a charge transport layer incorporating a silicon-containingtriarylamine compound of the present invention is formed as a thin filmon the charge generation layer. The film is formed mainly by coating,specifically, the silicon-containing triarylamine compound of thepresent invention is dissolved in a solvent in the presence of a binderadded as needed, and this solution is coated and then dried on thecharge generation layer.

Any solvent can be used with no limitation, as long as it dissolves thecompound described above and the binder used as needed and it does notdissolve the charge generation layer.

Any binder used as needed can be used with no limitation, as long as itis an insulating resin. Examples of such binders include condensationpolymers such as polycarbonate, polyarylate, polyester and polyamide;addition polymers such as polyethylene, polystyrene, styrene-acrylatecopolymer, polyacrylate, polymethacrylate, polyvinylbutyral,polyacrylonitrile, polyacrylamide, acrylonitrile-butadiene copolymer,polyvinyl chloride and vinyl chloride-vinyl acetate copolymer; andothers such as polysulfone, polyether sulfone and silicone resin. Thesebinders may be used singly or in combination.

Of these substances, polycarbonate resin, particularly a polycarbonateresin having a repeating unit represented by the formula (78): ##STR13##(wherein R₅, R₆, R₇, R₈, R₉, R₁₀, R₁₁ and R₁₂, which may be identical ornot, independently represent a hydrogen atom, a halogen atom or an alkylgroup) (generally referred to as polycarbonate Z resin) is preferredsince it offers excellent coating composition storage stability and isless liable to coating defect.

With respect to the formula (78), R₅ through R₁₂, which may be identicalor not, independently represent a hydrogen atom, a halogen atom, or analkyl group, and the halogen atom may be any one of fluorine, chlorine,bromine and iodine atoms, with preference given to chlorine atom. Also,when they represent an alkyl group, it is a linear or branched alkylgroup having a carbon number of 1 to 4, and examples include methyl,ethyl, n-propyl, isopropyl and n-butyl, with preference given to methyl.

Such a polycarbonate resin can easily be obtained by a known method suchas the reaction of substituted or unsubstituted1,1-bis(4-hydroxyphenyl)cyclohexane and phosgene (Angewandte Chemie,vol. 68, p. 633 (1956)] or the ester exchange reaction with a diester ofcarbonic acid such as diphenyl carbonate. A commercially availableproduct produced by Mitsubishi Gas Chemical Co., Inc. or by TeijinChemicals Co., Ltd. may also be used.

As in a compound having the repeating unit represented by the formula(78) described above, introduction of a cyclohexyl group into the mainchain of polycarbonate resin reduces its sliding resistance and makes itpossible to increase the toughness without causing a change in its glasstransition point. Therefore, a photoreceptor for electrophotographyincorporating said polycarbonate Z resin permits minimization ofabrasion by toner, paper, cleaning blade, etc. in theelectrophotographic process. Examples of the polycarbonate resin havingthe repeating unit represented by the formula (78) for the presentinvention are given below [Example Compounds (79) through (83)], withpreference given to Example Compound (79) since it is easy tosynthesize, but these are not to be construed as limitative on theinvention. ##STR14##

The number average molecular weight of these polycarbonate Z resins ispreferably 5,000 to 100,000. If the molecular weight is below thisrange, satisfactory mechanical strength is not obtained, and abrasionresistance cannot be obtained. If the molecular weight exceeds 100,000,the viscosity becomes too high upon coating to ensure good workability.The glass transition point is 50° C. to 200° C., between which rangeimproved abrasion resistance is obtained. If the glass transition pointis below this range, undesirable degradation occurs in environmentalproperties. If the glass transition point exceeds 200° C., brittlenessoccurs and abrasive deterioration becomes severe.

The amount of binder used is 0.1 to 3 parts by weight per each part ofthe silicon-containing triarylamine compound of the present invention,preferably 0.1 to 2 parts by weight. If the binder amount exceeds thisrange, the charge transport material concentration in the chargetransport layer decreases and the sensitivity lowers.

Also, in the present invention, the known charge transport materialsdescribed above can be used in combination where necessary.

Any coating means can be used to coat the charge transport layer with nolimitation. Examples of useful means include dip coater, bar coater,calender coater, gravure coater and spin coater, and electrodepositioncoating is also possible.

The thickness of the charge transport layer thus formed is preferably 10to 50 μm, more preferably 10 to 30 μm. If the thickness exceeds 50 μm,more time is required for charge transport, and the possibility ofcharge trapping increases, which may cause sensitivity reduction. If thethickness is below 10 μm, the mechanical strength decreases and the lifetime of the photoreceptor shortens.

A photoreceptor for electrophotography incorporating asilicon-containing triarylamine compound of the present invention in itscharge transport layer can be prepared as described above. Furthermore,an undercoat layer, an adhesion layer, a barrier layer, etc. can beformed as needed between the conductive substrate and the chargegeneration layer. Such layers can be prepared with any one of insulatingresin such as polyvinyl butyral, phenol resin or polyamide resin, adispersion of conductive inorganic fine powder in insulating resin, andconductive polymer prepared by ion doping into a conjugate polymer suchas polypyrrole or polythiophene. Also, a surface protective layer may beformed on the surface of the photoreceptor, which can be made of thesame material as with the undercoat layer, etc. described above.

In the use of the photoreceptor for electrophotography thus obtained,the surface of the photoreceptor is first negatively charged using acorona charger or the like. Exposure to light, which follows charging,causes the charge generation layer to generate charge pairs (positivecharge and negative charge). The positive charge is injected into thecharge transport layer, through which it is transported to the surfaceof the photoreceptor, where the surface negative charge is neutralized.The negative charge remains unneutralized in the unexposed portion. Inthe case of ordinary development, a positively charging toner is used,and it adheres to this portion where the negative charge remainsunneutralized and is developed thereon. In the case of reversaldevelopment, a negatively charging toner is used, and it adheres to thecharge-neutralized potion and is developed thereon. The photoreceptorfor electrophotogrpahy according to the present invention can be usedfor any development process, providing high image quality.

In the present invention, it is also possible to prepare a photoreceptorfor electrophotography by forming a charge transport layer on aconductive substrate in advance and then forming a charge generationlayer thereon. In this case, the surface of the photoreceptor is firstpositively charged and exposed to light, whereafter the resultingnegative charge neutralizes the surface charge of the photoreceptor,while the positive charge is transported to the conductive substratethrough the charge transport layer.

It is also possible to prepare the photoreceptor as a single-layerphotoreceptor wherein a charge generation material and a chargetransport material are contained in the same layer. In this case, thecharge generation material and the charge transport material aredispersed and dissolved in the presence of a binder and the resultingdispersion is coated on the substrate to a film thickness of 10 to 30μm.

EXAMPLES

The present invention is hereinafter described in more detail by meansof the following examples, but the invention is not by any means limitedto these examples.

EXAMPLE 1 Synthesis of 4,4',4"-tris(trimethylsilylmethyl)triphenylamine(Example Compound (8))

1.0 g (40 mmol) of metallic magnesium was placed in a 200-ml four-neckedflask equipped with a mechanical stirrer, a condenser, a nitrogen-inlettube and a dropping funnel, and the inside atmosphere was replaced withnitrogen. 100 ml of diethyl ether was added and stirring was initiated.To this solution, 20 ml of a diethyl ether solution of 3.9 g (10 mmol)of 4,4',4"-tris(chloromethyl)triphenylamine was gradually addeddropwise. When about 5 ml was added, mild reflux began. Under refluxconditions, the remainder of the diethyl ether solution was added. Aftercompletion of the addition, reflux was continued for 1 more hour. TheGrignard solution thus obtained was cooled to room temperature, and then20 ml of a diethyl ether solution of 3.3 g (30 mmol) ofchlorotrimethylsilane was gradually added dropwise under ice cooling.After completion of the addition, the reaction mixture was stirred underreflux conditions for 2 hours. Then, the mixture was cooled on ice waterbath, and 50 ml of water was added for hydrolysis. The ether layer wasextracted and washed with a saturated aqueous solution of sodiumhydrogen carbonate and then with two portions of water, followed bydrying with anhydrous sodium sulfate. After drying, the diethyl etherwas distilled off to yield a white solid, which was then recrystallizedwith n-hexane/toluene (2/1) to yield 3.6 g of the desired product (yield71%).

m.p.: 145.0°-146.8° C.

    ______________________________________                                        elementary analysis: (C.sub.30 H.sub.45 NSi.sub.3)                                     Calculated (%)                                                                          Found (%)                                                  ______________________________________                                        C          71.57       71.29                                                  H          8.95        8.99                                                   N          2.78        2.66                                                   Si         16.70       17.06                                                  ______________________________________                                    

EXAMPLE 2 Synthesis of 4,4',4"-tris(triethylsilylmethyl)triphenylamine(Example Compound (9))

1.0 g (40 mmol) of metallic magnesium was placed in a 200-ml four-neckedflask equipped with a mechanical stirrer, a condenser, a nitrogen-inlettube and a dropping funnel, and the inside atmosphere was replaced withnitrogen. 100 ml of diethyl ether was added and stirring was initiated.To this solution, 20 ml of a diethyl ether solution of 4.9 g (30 mmol)of chloromethyltriethylsilane was gradually added dropwise. When about 5ml was added, mild reflux began. Under reflux conditions, the remainderof the diethyl ether solution was added. After completion of theaddition, reflux was continued for 1 more hour. The Grignard solutionthus obtained was cooled to room temperature, and then 5 mg of NiCl₂(dppe) was added at room temperature. Further 20 ml of a diethyl ethersolution of 4.8 g (10 mmol) of 4,4',4"-tribromotriphenylamine wasgradually added dropwise under ice cooling. After completion of theaddition, the reaction mixture was stirred under reflux conditions for 8hours. Then, the mixture was cooled on ice water bath, and 50 ml ofwater was added for hydrolysis. The ether layer was extracted and washedwith a saturated aqueous solution of sodium hydrogen carbonate and thenwith two portions of water, followed by drying with anhydrous sodiumsulfate. After drying, the diethyl ether was distilled off to yield awhite solid, which was then recrystallized with n-hexane/toluene (5/1)to yield 4.8 g of the desired product (yield 76%).

m.p.: 128.6°-130.4° C.

    ______________________________________                                        elementary analysis: (C.sub.39 H.sub.63 NSi.sub.3)                                     Calculated (%)                                                                          Found (%)                                                  ______________________________________                                        C          74.40       74.20                                                  H          10.02       10.23                                                  N          2.23        2.11                                                   Si         13.35       13.46                                                  ______________________________________                                    

EXAMPLE 3 Synthesis of bis(4-diphenylaminophenylmethyl)dimethylsilane(Example Compound (16))

0.6 g (24.9 mmol) of metallic magnesium was placed in a 200-mlfour-necked flask equipped with a mechanical stirrer, a condenser, anitrogen-inlet tube and a dropping funnel, and the inside atmosphere wasreplaced with nitrogen. 100 ml of diethyl ether was added and stirringwas initiated. To this solution, 20 ml of a diethyl ether solution of5.9 g (20 mmol) of 4-chloromethyltriphenylamine was gradually addeddropwise. When about 5 ml was added, mild reflux began. Under refluxconditions, the remainder of the diethyl ether solution was added. Aftercompletion of the addition, reflux was continued for 1 more hour. TheGrignard solution thus obtained was cooled to room temperature, and then20 ml of a diethyl ether solution of 1.3 g (10 mmol) ofdichlorodimethylsilane was gradually added dropwise under ice cooling.After completion of the addition, the reaction mixture was stirred underreflux conditions for 2 hours. Then, the mixture was cooled on ice waterbath, and 50 ml of water was added for hydrolysis. The ether layer wasextracted and washed with a saturated aqueous solution of sodiumhydrogen carbonate and then with two portions of water, followed bydrying with anhydrous sodium sulfate. After drying, the diethyl etherwas distilled off to yield a white solid, which was then recrystallizedwith n-hexane/toluene (2/1) to yield 8.8 g of the desired product (yield73%).

m.p.: 125.4°-126.8° C.

    ______________________________________                                        elementary analysis: (C.sub.40 H.sub.38 N.sub.2 Si)                                    Calculated (%)                                                                          Found (%)                                                  ______________________________________                                        C          83.62       83.66                                                  H          6.62        6.88                                                   N          4.88        4.58                                                   Si         4.88        4.88                                                   ______________________________________                                    

EXAMPLE 4 Synthesis of bis(4-diphenylaminophenylmethyl)diethylsilane(Example Compound (17))

0.6 g (24.9 mmol) of metallic magnesium was placed in a 200-mlfour-necked flask equipped with a mechanical stirrer, a condenser, anitrogen-inlet tube and a dropping funnel, and the inside atmosphere wasreplaced with nitrogen. 100 ml of diethyl ether was added and stirringwas initiated. To this solution, 20 ml of a diethyl ether solution of3.7 g (20 mmol) of bis(chloromethyl)diethylsilane was gradually addeddropwise. When about 5 ml was added, mild reflux began. Under refluxconditions, the remainder of the diethyl ether solution was added. Aftercompletion of the addition, reflux was continued for 1 more hour. TheGrignard solution thus obtained was cooled to room temperature, and then6 mg of NiCl₂ (dppe) was added at room temperature. Further 20 ml of adiethyl ether solution of 13.0 g (40 mmol) of 4-bromotriphenylamine wasgradually added dropwise under ice cooling. After completion of theaddition, the reaction mixture was stirred under reflux conditions for 8hours. Then, the mixture was cooled on ice water bath, and 50 ml ofwater was added for hydrolysis. The ether layer was extracted and washedwith a saturated aqueous solution of sodium hydrogen carbonate and thenwith two portions of water, followed by drying with anhydrous sodiumsulfate. After drying, the diethyl ether was distilled off to yield awhite solid, which was then recrystallized with n-hexane/toluene (3/1)to yield 19.7 g of the desired product (yield 78%).

m.p.: 115.0°-117.3° C.

    ______________________________________                                        elementary analysis: (C.sub.42 H.sub.42 N.sub.2 Si)                                    Calculated (%)                                                                          Found (%)                                                  ______________________________________                                        C          83.72       83.65                                                  H          6.98        7.26                                                   N          4.65        4.52                                                   Si         4.65        4.57                                                   ______________________________________                                    

EXAMPLE 5 Synthesis of tris(4-diphenylaminophenylmethyl)methylsilane(Example Compound (48))

0.6 g (24.9 mmol) of metallic magnesium was placed in a 200-mlfour-necked flask equipped with a mechanical stirrer, a condenser, anitrogen-inlet tube and a dropping funnel, and the inside atmosphere wasreplaced with nitrogen. 100 ml of diethyl ether was added and stirringwas initiated. To this solution, 20 ml of a diethyl ether solution of5.9 g (20 mmol) of 4-chloromethyltriphenylamine was gradually addeddropwise. When about 5 ml was added, mild reflux began. Under refluxconditions, the remainder of the diethyl ether solution was added. Aftercompletion of the addition, reflux was continued for 1 more hour. TheGrignard solution thus obtained was cooled to room temperature, and then20 ml of a diethyl ether solution of 1.0 g (6.7 mmol) ofdichlorodimethylsilane was gradually added dropwise under ice cooling.After completion of the addition, the reaction mixture was stirred underreflux conditions for 2 hours. Then, the mixture was cooled on ice waterbath, and 50 ml of water was added for hydrolysis. The ether layer wasextracted and washed with a saturated aqueous solution of sodiumhydrogen carbonate and then with two portions of water, followed bydrying with anhydrous sodium sulfate. After drying, the diethyl etherwas distilled off to yield a white solid, which was then recrystallizedwith n-hexane/toluene (1/1) to yield 3.8 g of the desired product (yield70%).

m.p.: 197.4°-199.2° C.

    ______________________________________                                        elementary analysis: (C.sub.58 H.sub.51 N.sub.3 Si)                                    Calculated (%)                                                                          Found (%)                                                  ______________________________________                                        C          85.19       85.01                                                  H          6.24        6.35                                                   N          5.14        5.06                                                   Si         3.43        3.58                                                   ______________________________________                                    

EXAMPLE 6 Synthesis of 4-trimethylsilylmethyltriphenylamine (ExampleCompound (60))

1.0 g (40 mmol) of metallic magnesium was placed in a 200-ml four-neckedflask equipped with a mechanical stirrer, a condenser, a nitrogen-inlettube and a dropping funnel, and the inside atmosphere was replaced withnitrogen. 100 ml of diethyl ether was added and stirring was initiated.To this solution, 20 ml of a diethyl ether solution of 8.8 g (30 mmol)of 4-chloromethyltriphenylamine was gradually added dropwise. When about5 ml was added, mild reflux began. Under reflux conditions, theremainder of the diethyl ether solution was added. After completion ofthe addition, reflux was continued for 1 more hour. The Grignardsolution thus obtained was cooled to room temperature, and then 20 ml ofa diethyl ether solution of 3.3 g (30 mmol) of chlorotrimethylsilane wasgradually added dropwise under ice cooling. After completion of theaddition, the reaction mixture was stirred under reflux conditions for 2hours. Then, the mixture was cooled on ice water bath, and 50 ml ofwater was added for hydrolysis. The ether layer was extracted and washedwith a saturated aqueous solution of sodium hydrogen carbonate and thenwith two portions of water, followed by drying with anhydrous sodiumsulfate. After drying, the diethyl ether was distilled off to yield awhite solid, which was then recrystallized with n-hexane/ethyl acetate(5/1) to yield 7.2 g of the desired product (yield 82%).

m.p: 186.0°-187.5° C.

    ______________________________________                                        elementary analysis: (C.sub.22 H.sub.25 NSi)                                           Calculated (%)                                                                          Found (%)                                                  ______________________________________                                        C          79.76       79.62                                                  H          7.55        7.71                                                   N          4.23        4.19                                                   Si         8.46        8.48                                                   ______________________________________                                    

EXAMPLE 7 Synthesis of 4-triethylsilylmethyltriphenylamine (ExampleCompound (61))

1.0 g (40 mmol) of metallic magnesium was placed in a 200-ml four-neckedflask equipped with a mechanical stirrer, a condenser, a nitrogen-inlettube and a dropping funnel, and the inside atmosphere was replaced withnitrogen. 100 ml of diethyl ether was added and stirring was initiated.To this solution, 20 ml of a diethyl ether solution of 4.9 g (30 mmol)of chloromethyltriethylsilane was gradually added dropwise. When about 5ml was added, mild reflux began. Under reflux conditions, the remainderof the diethyl ether solution was added. After completion of theaddition, reflux was continued for 1 more hour. The Grignard solutionthus obtained was cooled to room temperature, and then 5 mg of NiCl₂(dppe) was added at room temperature. Further 20 ml of a diethyl ethersolution of 9.7 g (30 mmol) of 4-bromotriphenylamine was gradually addeddropwise under ice cooling. After completion of the addition, thereaction mixture was stirred under reflux conditions for 8 hours. Then,the mixture was cooled on ice water bath, and 50 ml of water was addedfor hydrolysis. The ether layer was extracted and washed with asaturated aqueous solution of sodium hydrogen carbonate and then withtwo portions of water, followed by drying with anhydrous sodium sulfate.After drying, the diethyl ether was distilled off to yield a whitesolid, which was then recrystallized with n-hexane/toluene (5/1) toyield 9.3 g of the desired product (yield 83%).

m.p.: 172.1°-174.5° C.

    ______________________________________                                        elementary analysis: (C.sub.25 H.sub.31 NSi)                                           Calculated (%)                                                                          Found (%)                                                  ______________________________________                                        C          80.43       80.23                                                  H          8.31        8.44                                                   N          3.75        3.95                                                   Si         7.51        7.38                                                   ______________________________________                                    

EXAMPLES 8 THROUGH 19

Example Compounds (10) through (15) can be synthesized in the samemanner as in Example 1 or 2. Example Compounds (18) through (47) can besynthesized in the same manner as in Example 3 or 4. Example Compounds(49) through (59) can be synthesized in the same manner as in Example 5.Example Compounds (62) through (77) can be synthesized in the samemanner as in Example 6 or 7. The yield, melting point and elementaryanalysis data of some of the compounds obtained by these methods aregiven in Table 1.

                                      TABLE 1                                     __________________________________________________________________________                                   Elementary Analysis (%)                        Example                                                                            Example Compound                                                                        Yield (%)                                                                           m.p. (°C.)                                                                       C  H  N  Si                                    __________________________________________________________________________    Ex. 8                                                                              (15)      80    174.3-                                                                              Calc.                                                                             73.78                                                                            8.50                                                                             2.53                                                                             15.19                                                      176.2 Found                                                                             73.75                                                                            8.70                                                                             2.41                                                                             15.14                                 Ex. 9                                                                              (18)      75    103.5-                                                                              Calc.                                                                             83.89                                                                            6.98                                                                             4.65                                                                             4.65                                                       104.8 Found                                                                             83.77                                                                            7.10                                                                             4.68                                                                             4.45                                  Ex. 10                                                                             (19)      85    125.5-                                                                              Calc.                                                                             83.77                                                                            7.14                                                                             4.54                                                                             4.55                                                       127.3 Found                                                                             83.51                                                                            7.32                                                                             4.48                                                                             4.69                                  Ex. 11                                                                             (22)      72    102.6-                                                                              Calc.                                                                             83.89                                                                            7.60                                                                             4.25                                                                             4.26                                                       105.0 Found                                                                             83.75                                                                            7.77                                                                             4.14                                                                             4.34                                  Ex. 12                                                                             (23)      70     75.3-                                                                              Calc.                                                                             83.97                                                                            7.87                                                                             4.08                                                                             4.08                                                        77.2 Found                                                                             83.74                                                                            7.95                                                                             4.14                                                                             4.17                                  Ex. 13                                                                             (24)      81    142.0-                                                                              Calc.                                                                             84.96                                                                            6.78                                                                             4.13                                                                             4.13                                                       144.0 Found                                                                             84.78                                                                            6.97                                                                             4.18                                                                             4.07                                  Ex. 14                                                                             (31)      77    115.5-                                                                              Calc.                                                                             83.89                                                                            7.60                                                                             4.25                                                                             4.26                                                       117.0 Found                                                                             83.78                                                                            7.70                                                                             4.45                                                                             4.07                                  Ex. 15                                                                             (32)      74     84.2-                                                                              Calc.                                                                             83.72                                                                            6.98                                                                             4.65                                                                             4.65                                                        86.2 Found                                                                             83.55                                                                            7.10                                                                             4.55                                                                             4.80                                  Ex. 16                                                                             (33)      79     65.3 Calc.                                                                             83.81                                                                            7.30                                                                             4.44                                                                             4.45                                                        66.2 Found                                                                             83.79                                                                            7.47                                                                             4.39                                                                             4.35                                  Ex. 17                                                                             (35)      76     87.5-                                                                              Calc.                                                                             83.89                                                                            7.60                                                                             4.25                                                                             4.26                                                        88.7 Found                                                                             83.71                                                                            7.78                                                                             4.12                                                                             4.39                                  Ex. 18                                                                             (49)      75    187.6-                                                                              Calc.                                                                             85.20                                                                            6.38                                                                             5.05                                                                             3.37                                                       189.0 Found                                                                             85.05                                                                            6.54                                                                             5.15                                                                             3.26                                  Ex. 19                                                                             (71)      76    120.4-                                                                              Calc.                                                                             80.43                                                                            8.31                                                                             3.75                                                                             7.51                                                       122.1 Found                                                                             80.24                                                                            8.40                                                                             3.63                                                                             7.73                                  __________________________________________________________________________

EXAMPLE 20 Synthesis of polycarbonate Z resin (Example Compound (79))

100 g of 1,1-bis(4-hydroxyphenyl)cyclohexane, 50 g of sodium hydroxide,900 g of water, 500 g of methylene chloride and 2 g of p-t-butylphenolwere placed in a 2-l four-necked flask equipped with a mechanicalstirrer, a condenser and a gas-inlet tube, followed by vigorousstirring. 37 g of phosgene was bubbled at room temperature forpolymerization. After completion of the polymerization, the methylenechloride layer was extracted and added dropwise to 5 l of diethyl etherfor reprecipitation. The obtained white solid was filtered and dried toyield 104 g of the desired product.

The number average molecular weight of the polycarbonate Z resin thusobtained was estimated at about 50,000 as polystyrene by liquidchromatography, and its glass transition point was 141° C.

EXAMPLE 21

4.1 g of X-form metal-free phthalocyanine, 4.1 g of polyvinylbutyral(S-LEC BM-2, product of Sekisui Chemical Co., Ltd.), 200 g ofcyclohexanone, and 650 g of glass beads (1 mm in diameter) were placedin a sand mill, followed by 4 hours of dissolution and dispersion toyield a coating composition for charge generation layer. This coatingcomposition was coated on a dia-turned aluminum cylinder (40 mm indiameter) by dipping method and dried to a final film thickness of 0.15μm.

Next, 80 g of the compound represented by Example Compound (8) and 80 gof a polycarbonate Z resin (number average molecular weight=50,000)having the repeating unit represented by Example Compound (79) weredissolved in 450 g of dioxane to yield a coating composition for chargetransport layer. This coating composition was coated on the aluminumcylinder which had been coated with the charge generation layerdescribed above by dipping method to a final film thickness of 25 μm.

The drum-shaped photoreceptor for electrophotography thus prepared wasevaluated as to electrophotographic properties using a drum xerographytester (electrostatic voltmeter 362A, product of Trek, Inc.; lightsource: semiconductor laser 790 nm). When the photoreceptor was chargedwith -5.5 kV corona voltage, the initial surface potential V₀ was foundto be -880 V. After the photoreceptor was kept standing in the dark for2 seconds, the surface potential V₂ became -870 V. Then, 790 nmsemiconductor laser was irradiated, and the half decay exposure E_(1/2)was found to be 0.28 μJ/cm² and the residual potential V_(R) was -8.8 V.

Next, after the procedure described above was repeated in 50,000 cycles,the V₀, V₂, E_(1/2) and V_(R) were found to be -860 V, -850 V, 0.28μJ/cm², and -16.5 V, respectively, i.e., the performance of thephotoreceptor showed almost no degradation.

Next, a photoreceptor for electrophotography prepared in the same manneras above was loaded on a commercial laser beam printer of the bladecleaning and reversal development type and a print test was conducted.Even after 50,000 copies were taken, there occurred almost no filmthickness reduction, nor was there any damage which might affect imagequality. Also, the obtained images maintained a high image density andhad no deterioration.

The photoreceptor for electrophotography according to the presentinvention was thus found to be very excellent in sensitivity anddurability.

EXAMPLES 22 THROUGH 32

Photoreceptors were prepared and tested for performance in the samemanner as in Example 21 except that the compounds listed in Table 2 wereused in place of the silicon-containing triarylamine compoundrepresented by Example Compound (8) as the charge transport material.The results are given in Table 2.

As seen in Table 2, all the photoreceptor samples remained excellent inphotoreceptor properties both in the initial stage and even after 50,000copies were taken.

After 50,000 copies were taken with the photoreceptor loaded on theprinter, no film thickness reduction occurred in any of thephotoreceptors, with high image density maintained in allphotoreceptors.

                                      TABLE 2                                     __________________________________________________________________________                               photoreceptor properties                           Example                                                                            charge transport material                                                                           V.sub.0 (V)                                                                       V.sub.2 (V)                                                                       E.sub.1/2 (μJ/cm.sup.2)                                                           V.sub.R (V)                         __________________________________________________________________________    Ex. 22                                                                             (9)          initial stage                                                                          -880                                                                              -870                                                                              0.28   -8.0                                                  after 50,000 copies                                                                    -870                                                                              -860                                                                              0.28   -15.0                               Ex. 23                                                                             (16)         initial stage                                                                          -870                                                                              -860                                                                              0.27   -5.8                                                  after 50,000 copies                                                                    -860                                                                              -850                                                                              0.27   -6.8                                Ex. 24                                                                             (17)         initial stage                                                                          -860                                                                              -850                                                                              0.27   -8.0                                                  after 50,000 copies                                                                    -850                                                                              -840                                                                              0.27   -12.0                               Ex. 25                                                                             (19)         initial stage                                                                          -870                                                                              -850                                                                              0.26   -7.2                                                  after 50,000 copies                                                                    -860                                                                              -850                                                                              0.27   -13.8                               Ex. 26                                                                             (22)         initial stage                                                                          -840                                                                              -830                                                                              0.26   -6.3                                                  after 50,000 copies                                                                    -840                                                                              -820                                                                              0.27   -18.0                               Ex. 27                                                                             (32)         initial stage                                                                          -880                                                                              -870                                                                              0.29   -11.8                                                 after 50,000 copies                                                                    -870                                                                              -860                                                                              0.31   -25.1                               Ex. 28                                                                             (35)         initial stage                                                                          -860                                                                              - 840                                                                             0.28   -9.9                                                  after 50,000 copies                                                                    -850                                                                              -840                                                                              0.29   -15.6                               Ex. 29                                                                             (48)         initial stage                                                                          -880                                                                              -860                                                                              0.28   -7.1                                                  after 50,000 copies                                                                    -860                                                                              -840                                                                              0.28   -9.0                                Ex. 30                                                                             (49)         initial stage                                                                          -870                                                                              -860                                                                              0.26   -6.0                                                  after 50,000 copies                                                                    -850                                                                              -840                                                                              0.27   -15.0                               Ex. 31                                                                             (60)         initial stage                                                                          -870                                                                              -860                                                                              0.27   -7.3                                                  after 50,000 copies                                                                    -860                                                                              -850                                                                              0.28   -19.2                               Ex. 32                                                                             (61)         initial stage                                                                          -880                                                                              -870                                                                              0.28   -6.0                                                  after 50,000 copies                                                                    -870                                                                              -860                                                                              0.28   -13.0                               __________________________________________________________________________

EXAMPLES 33 THROUGH 35

Photoreceptors were prepared and tested for performance in the samemanner as in Example 23 except that the polycarbonate Z resins listed inTable 3 were used in place of the polycarbonate Z resins having therepeating unit represented by Example Compound (79). The results aregiven in Table 3.

As seen in Table 3, all the photoreceptor samples remained excellent inphotoreceptor properties both in the initial stage and even after 50,000copies were taken.

After 50,000 copies were taken with the photoreceptor loaded on theprinter, no film thickness reduction occurred in any of thephotoreceptors, with high image density maintained in allphotoreceptors.

                                      TABLE 3                                     __________________________________________________________________________         repeating unit of photoreceptor properties                               Example                                                                            polycarbonate Z   V.sub.0 (V)                                                                       V.sub.2 (V)                                                                       E.sub.1/2 (μJ/cm.sup.2)                                                           V.sub.R (V)                             __________________________________________________________________________    Ex. 33                                                                             (80)     initial stage                                                                          -870                                                                              -860                                                                              0.27   -7                                                    after 50,000 copies                                                                    -860                                                                              -850                                                                              0.27   -16                                     Ex. 34                                                                             (81)     initial stage                                                                          -870                                                                              -850                                                                              0.27   -8                                                    after 50,000 copies                                                                    -870                                                                              -860                                                                              0.27   -12                                     Ex. 35                                                                             (82)     initial stage                                                                          -870                                                                              -860                                                                              0.28   -6                                                    after 50,000 copies                                                                    -860                                                                              -840                                                                              0.28   -16                                     __________________________________________________________________________

EXAMPLE 36

10 g of polyamide resin (AMIRAN CM-8000, product of Toray Industries,Inc.) was dissolved in 200 g of methanol/n-butanol (2/1) to yield acoating composition for undercoat layer, which was coated on adia-turned aluminum cylinder (40 mm in diameter) by dipping method anddried to a final film thickness of 0.10 μm.

20 g of X-form metal-free phthalocyanine, 80 g of the compoundrepresented by Example Compound (16), 80 g of a polycarbonate resin(number average molecular weight=50,000) having the repeating unitrepresented by Example Compound (79), 450 g of dioxane, and 650 g ofglass beads (1 mm in diameter) were placed in a sand mill, followed by 4hours of dissolution and dispersion to yield a coating composition forsingle layer structure. This coating composition was coated on theundercoated aluminum cylinder by dipping method to a final filmthickness of 25 μm.

The drum-shaped photoreceptor for electrophotography thus prepared wasevaluated as to electrophotographic properties using a drum xerographytester. When the photoreceptor was charged with -5.5 kV corona voltage,the initial surface potential V₀ was found to be -900 V. After thephotoreceptor was kept standing in the dark for 2 seconds, the surfacepotential V₂ became -870 V. Then, 790 nm semiconductor laser wasirradiated, and the half decay exposure E_(1/2) was found to be 0.37μJ/cm² and the residual potential V_(R) was -15.2 V.

Next, after the procedure described above was repeated in 50,000 cycles,the V₀, V₂, E_(1/2) and V_(R) were found to be -890 V, -870 V, 0.38μJ/cm², and -26.5 V, respectively, i.e., the performance of thephotoreceptor showed almost no degradation.

Next, a photoreceptor for electrophotography prepared in the same manneras above was loaded on a commercial laser beam printer of the bladecleaning and reversal development type and a print test was conducted.Even after 50,000 copies were taken, there occurred almost no filmthickness reduction, nor was there any damage which might affect imagequality. Also, the obtained images maintained a high image density andhad no deterioration.

The photoreceptor for electrophotography according to the presentinvention was thus found to be very excellent in sensitivity anddurability.

EXAMPLE 37

5 g of dibromoanthanthrone and 5 g of butyral resin (S-LEC BM-2, productof Sekisui Chemical Co., Ltd.) were dispersed and dissolved in 90 ml ofcyclohexanone and kneaded in a ball mill for 24 hours. The obtaineddispersion was coated on an aluminum plate using a bar coater and driedto a final film thickness of 0.15 μm to yield a charge generation layer.Next, 5 g of the compound represented by Example Compound (8) and 5 g ofa polycarbonate A resin (LEXAN® 131-111, product of Engineering PlasticsK. K.) were dissolved in 90 ml of dioxane. The resulting solution wascoated on the charge generation layer formed in advance using a bladecoater and dried to a final film thickness of 25 μm to yield a chargetransport layer.

The photoreceptor for electrophotography thus prepared was charged with-5.5 kV corona voltage using the test equipment for electrostatic paperanalyzer EPA-8100, produced by Kawaguchi Denki Seisakusho K. K.; theinitial surface potential V₀ was found to be -870 V. After thephotoreceptor was kept standing in the dark for 2 seconds, the surfacepotential V₂ became -850 V. Then, the photoreceptor was irradiated witha halogen lamp of a illuminance of 5 lux, and the half decay exposureE₁₇₈ was found to be 0.91 lux·sec and the residual potential V_(R) was-9.3 V.

Next, after the procedure described above was repeated in 5,000 cycles,V₀, V₂, E_(1/2) and V_(R) were found to be -870 V, -850 V, 1.01 lux·sec,and -10.5 V, respectively, i.e., the photoreceptor proved to beexcellent in photoreceptor performance and high durability.

EXAMPLES 38 THROUGH 49

Photoreceptors were prepared and tested for performance in the samemanner as in Example 37 except that the compounds listed in Table 4 wereused in place of the compound represented by Example Compound (8) ascharge transport materials. The results are given in Table 4.

                                      TABLE 4                                     __________________________________________________________________________                               photoreceptor properties                           Example                                                                            charge transport material                                                                           V.sub.0 (V)                                                                       V.sub.2 (V)                                                                       E.sub.1/2 (lux · sec)                                                       V.sub.R (V)                         __________________________________________________________________________    Ex. 38                                                                              (9)         initial stage                                                                          -870                                                                              -850                                                                              1.0    -5.1                                                  after 5,000 copies                                                                     -860                                                                              -840                                                                              1.1    -8.9                                Ex. 39                                                                             (15)         initial stage                                                                          -860                                                                              -850                                                                              1.0    -6.8                                                  after 5,000 copies                                                                     -860                                                                              -850                                                                              1.0    -10.4                               Ex. 40                                                                             (16)         initial stage                                                                          -860                                                                              -850                                                                              1.0    -5.2                                                  after 5,000 copies                                                                     -860                                                                              -850                                                                              1.1    -7.5                                Ex. 41                                                                             (18)         initial stage                                                                          -860                                                                              -840                                                                              1.1    -5.1                                                  after 5,000 copies                                                                     -850                                                                              -840                                                                              1.1    -10.3                               Ex. 42                                                                             (23)         initial stage                                                                          -880                                                                              -870                                                                              1.0    -3.7                                                  after 5,000 copies                                                                     -860                                                                              -850                                                                              1.2    -10.8                               Ex. 43                                                                             (24)         initial stage                                                                          -850                                                                              840 1.0    -8.0                                                  after 5,000 copies                                                                     -850                                                                              -830                                                                              1.0    -10.1                               Ex. 44                                                                             (31)         initial stage                                                                          -870                                                                              - 870                                                                             1.1    -12.0                                                 after 5,000 copies                                                                     -860                                                                              -850                                                                              1.1    -14.6                               Ex. 45                                                                             (33)         initial stage                                                                          -850                                                                              -840                                                                              1.2    -8.8                                                  after 5,000 copies                                                                     -850                                                                              -840                                                                              1.2    -15.2                               Ex. 46                                                                             (36)         initial stage                                                                          -860                                                                              850 1.2    -10.9                                                 after 5,000 copies                                                                     -860                                                                              -850                                                                              1.2    -17.7                               Ex. 47                                                                             (48)         initial stage                                                                          -880                                                                              -870                                                                              1.0    -7.6                                                  after 5,000 copies                                                                     -870                                                                              -850                                                                              1.1    -15.3                               Ex. 48                                                                             (60)         initial stage                                                                          -870                                                                              -850                                                                              1.2    -8.3                                                  after 5,000 copies                                                                     -870                                                                              -850                                                                              1.2    -18.5                               Ex. 49                                                                             (71)         initial stage                                                                          -880                                                                              -870                                                                              1.2    -12.0                                                 after 5,000 copies                                                                     -870                                                                              -860                                                                              1.2    -25.2                               __________________________________________________________________________

COMPARATIVE EXAMPLE 1

A photoreceptor was prepared and tested for performance in the samemanner as in Example 21 except that 4,4', 4"-trimethyltriphenylamine wasused in place of Example Compound (8) as the charge transport material.

When the photoreceptor was charged with -5.5 kV corona voltage, theinitial surface potential V₀ was found to be -880 V. After thephotoreceptor was kept standing in the dark for 2 seconds, the surfacepotential V₂ became -860 V. Then, 790 nm semiconductor laser wasirradiated, and the half decay exposure E_(1/2) was found to be 0.89μJ/cm² and the residual potential V_(R) was -42.6 V.

Next, after the procedure described above was repeated in 50,000 cycles,the V₀, V₂, E_(1/2) and V_(R) were found to be -860 V, -820 V, 0.94μJ/cm² and -63.1 V, respectively, i.e., the performance of thephotoreceptor was worse than that of example 21.

Next, a photoreceptor for electrophotography prepared in the same manneras above was loaded on a commercial laser beam printer of the bladecleaning and reversal development type and a print test was conducted.Even after 50,000 copies were taken, there occurred almost no filmthickness reduction, nor was there any damage which might affect imagequality. But, the obtained images showed a low image density due to lowsensitivity.

COMPARATIVE EXAMPLE 2 Synthesis of 4-triethylsilyltriphenylamine

8.1 g (24.9 mmol) of 4-bromotriphenylamine was placed in a 200-mlfour-necked flask equipped with a mechanical stirrer, a condenser, anitrogen-inlet tube and a dropping funnel, and the inside atmosphere wasreplaced with nitrogen. 100 ml of diethyl ether was added and the4-bromotriphenylamine was dissolved therein. To this ether solution, 16ml of n-butyl lithium (1.6M hexane solution, 25.6 mmol) was graduallyadded dropwise at room temperature. After completion of the addition,the mixture was stirred at room temperature for 1 hour. Then, to thisreaction mixture, 20 ml of a diethyl ether solution of 3.8 g (24.9 mmol)of triethylchlorosilane was gradually added dropwise under refluxconditions. After completion of the addition, the reaction mixture wasstirred for 2 hours under reflux conditions. Then, under ice coolingconditions, 50 ml of water was added for hydrolysis. The ether layer wasextracted and washed with a saturated aqueous solution of sodiumhydrogen carbonate and then with two portions of water, followed bydrying with anhydrous sodium sulfate. After drying, the diethyl etherwas distilled off to yield a white liquid, which was then distilled toyield 6.5 g of the desired product (yield 73%).

b.p.: 187°-191° C. (0.3 mmHg)

Next, a photoreceptor was prepared and tested for performance in thesame manner as in the Example 21 except that4-triethylsilyltriphenylamine was used in place of Example Compound (8)as the charge transport material.

When the photoreceptor was charged with -5.5 kV corona voltage, theinitial surface potential V₀ was found to be -890 V. After thephotoreceptor was kept standing in the dark for 2 seconds, the surfacepotential V₂ became -880 V. Then, a semiconductor laser of anoscillating wavelength of 790 nm was irradiated, and the half decayexposure E_(1/2) was found to be 1.97 μJ/cm² and the residual potentialV_(R) was -315 V. Next, after the procedure described above was repeatedin 50,000 cycles, the V₀, V₂, E_(1/2) and V_(R) were found to be -1100V, -1070 V, 3.88 μJ/cm² and -433 V, respectively, i.e., the performanceof the photoreceptor was worse than that of example 21.

Next, a photoreceptor for electrophotography prepared in the same manneras above was loaded on a commercial laser beam printer of the bladecleaning and reversal development type and a print test was conducted.The obtained images showed a considerable low image density due to lowsensitivity, and the surface of the photoreceptor for electrophotographythus prepared was adhesive and also the cleaning of toner worsened since4-triethylsilyltriphenylamine was liquid.

What is claimed is:
 1. A compound represented by the formula (1):##STR15## wherein Q₂ and Q₃ independently represent a hydrogen atom or--CH₂ SiR₁ R₂ R₃ group (R₁, R₂ and R₃, which may be identical or not,independently represent an alkyl group, cycloalkyl group, aralkyl groupor aryl group which may be substituted); Ar₁, Ar₂ and Ar₃ independentlyrepresent an arylene group which may be substituted; Q₁ represents a--CH₂ SiR₁ R₂ R₃ group, --CH₂ SiR₁ R₂ R₄ group (R₄ represents thefollowing: ##STR16## wherein Q₂ and Q₃ independently represent ahydrogen atom) or --CH₂ SiR₁ R₄ R₄ group.
 2. A compound according toclaim 1 of the formula (2): ##STR17## wherein R₁, R₂, R₃, Ar₁, Ar₂ andAr₃ have the same definitions as in claim
 1. 3. A compound according toclaim 2 wherein R₁, R₂ and R₃ represent an alkyl group.
 4. A compoundaccording to claim 3 of the formula: ##STR18##
 5. A compound accordingto claim 1 of the formula (3): ##STR19## wherein R₁, R₂, Ar₁, Ar₂ andAr₃ have the same definitions as in claim 1, and Q₂ and Q₃ represent ahydrogen atom.
 6. A compound according to claim 5 wherein R₁ and R₂represent an alkyl group.
 7. A compound according to claim 6 of theformula: R1 ? ##STR20##
 8. A compound according to claim 1 of theformula (4): ##STR21## wherein R₁, Ar₁, Ar₂ and Ar₃ have the samedefinitions as in claim 1, and Q₂ and Q₃ represent a hydrogen atom.
 9. Acompound according to claim 8 wherein R₁ represents an alkyl group. 10.A compound according to claim 9 of the formula: ##STR22##
 11. A compoundaccording to claim 1 of the formula (5): ##STR23## wherein R₁, R₂, R₃,Ar₁, Ar₂ and Ar₃ have the same definitions as in claim 1, and Q₂ and Q₃represent a hydrogen atom.
 12. A compound according to claim 11 whereinR₁, R₂ and R₃ represent an alkyl group.
 13. A compound according toclaim 12 of the formula: ##STR24##
 14. A method for producing a compoundof claim 1 which comprises reacting a Grignard reagent represented bythe formula (1)': ##STR25## wherein Q₂ ' and Q₃ ' independentlyrepresent a hydrogen atom or --CH₂ MgX (X represents a halogen atom); Q₁' represents --CH₂ MgX; Ar₁, Ar₂ and Ar₃ have the same definitions as inclaim 1, with a silane compound represented by the formula (6):

    X.sub.1 SiR.sub.1 'R.sub.2 'R.sub.3 '                      (6)

wherein X₁ represents a halogen atom or alkoxy group; none, one or twoof R₁ ', R₂ ' and R₃ ' independently represent a halogen atom or alkoxygroup while the remaining one, two or three independently represent analkyl group, cycloalkyl group, aralkyl group or aryl group which may besubstituted.
 15. A method according to claim 14 which comprises reactinga Grignard reagent when Q₂ ' and Q₃ ' of the formula (1)' represent--CH₂ MgX, with a silane compound when all of R₁ ', R₂ ' and R₃ ' of theformula (6) independently represent an alkyl group, cycloalkyl group,aralkyl group or aryl group which may be substituted.
 16. A methodaccording to claim 14 which comprises reacting a Grignard reagent whenQ₂ ' and Q₃ ' of the formula (1)' represent a hydrogen atom, with asilane compound when one of R₁ ', R₂ ' and R₃ ' of the formula (6)represents a halogen atom or alkoxy group while the remaining twoindependently represent an alkyl group, cycloalkyl group, aralkyl groupor aryl group which may be substituted.
 17. A method according to claim14 which comprises reacting a Grignard reagent when Q₂ ' and Q₃ ' of theformula (1)' represent a hydrogen atom, with a silane compound when twoof R₁ ', R₂ ' and R₃ ' of the formula (6) independently represent ahalogen atom or alkoxy group while the remaining one represents an alkylgroup, cycloalkyl group, aralkyl group or aryl group which may besubstituted.
 18. A method according to claim 14 which comprises reactinga Grignard reagent when Q₂ ' and Q₃ ' of the formula (1)' represent ahydrogen atom, with a silane compound when all of R₁ ', R₂ ' and R₃ ' ofthe formula (6) independently represent an alkyl group, cycloalkylgroup, aralkyl group or aryl group which may be substituted.
 19. Amethod for producing a compound of claim 1 which comprises reacting acompound represented by the formula (7):

    R.sub.1 R.sub.2 R.sub.3 "SiCH.sub.2 MgX                    (7)

wherein R₃ " is identical with R₃ (R₃ has the same definition as inclaim 1) or represents --CH₂ MgX; R₁, R₂ and X have the same definitionsas in claim 1, with a halogenated triarylamine compound in the presenceof a coupling catalyst.
 20. A method according to claim 19 whichcomprises reacting a compound when R₃ " of the formula (7) is identicalwith R₃, with a tris(halogeno-aryl)amine compound in the presence of acoupling catalyst.
 21. A method according to claim 19 which comprisesreacting a compound when R₃ " of the formula (7) represents --CH₂ MgX,with a monohalogenated triarylamine compound in the presence of acoupling catalyst.
 22. A method according to claim 19 which comprisesreacting a compound when R₃ " of the formula (7) is identical with R₃,with a monohalogenated triarylamine compound in the presence of acoupling catalyst.